Double walled apparatuses, such as, for example, double walled exhaust gas catalytic converters and/or other containers, are often used to insulate an inner environment from an outer environment. Such apparatuses typically include an inner wall exposed to the inner environment which has a first temperature, an outer wall exposed to the outer environment which has a second temperature, and insulation disposed between the inner and outer walls. The first and second temperatures are often substantially different. Such temperature differences may result in a substantial difference in amounts of thermal expansion for the inner and outer walls. Differences in thermal expansion may produce adverse effects, such as, stress concentrations at connections between the inner and outer walls, geometry deformation of one or both of the inner and outer walls, and/or structural weakness which may result in undesirably short life cycles of the apparatuses.
U.S. Patent Application Publication No. 2005/0002836 (“the '836 application”) filed by Hardesty et al. discloses a gas treatment device comprising an inlet communicating exhaust gas into a housing. The '836 application also discloses a substrate disposed within the housing configured to support an exhaust gas catalyst and a retention device supporting the substrate radially within and spaced apart from the housing. The '836 application discloses two embodiments of the retention device, a fixed retention device and an unfixed retention device. The fixed retention device has a first end fixed via welding to the housing and a second end embedded within the substrate via a compression connection. The unfixed retention device has a first end engaging but not fixed to the housing and a second end engaging but not fixed to the substrate. Both the fixed and unfixed retention devices are configured to flexibly support the substrate with respect to the housing and account for differential thermal expansion.
Although the retention device of the '836 application may account for differential thermal expansion between the housing and the substrate, by being embedded within the substrate, the retention device may damage the substrate during assembly and/or operation. Additionally, the retention device of the '836 application may not suitably dampen vibrations between the housing and the substrate. Furthermore, the connection between the retention device and the substrate of the '836 application may be undesirably prone to loosening during operation.
The present disclosure is directed to overcoming one or more of the shortcomings set forth above.